This invention is related to the safety latch mechanism disclosed and claimed in U.S. Pat. No. 4,029,357. However, instead of using spring elements for swinging the latch bar upwardly into locking position, the present invention uses the force of gravity to swing the latch bar down into locking position and uses a positive lever action for lifting the bar out of latching position. By doing away with spring action to bias the latch bar into locking position, a more reliable and durable mechanism is provided.